A terminal, such as a mobile phone or a tablet computer, may be used to store a large quantity of data including private information of a user, such as the owner of the terminal. The terminal generally can be locked to prevent unauthorized use and to provide protection of the private information.
Conventional unlocking methods for the terminal include a numeric password, squared figures, fingerprint recognition, voice recognition, and face recognition. Although those methods may provide protection for the locked terminal, when a second user other than the owner tries to unlock the terminal, the conventional unlocking methods may only prompt the second user that an incorrect password has been inputted and request for another password input, and generally will not provide additional information. Also, the owner generally will not find out that the second user has tried to unlock the terminal, which may be a potential security risk for the terminal.